<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
   <div class="box">
        <!-- 头部 -->
    <header class="header">头部</header>
    <!-- 内容 -->
    <div class="mian">
        <div class="sidebar">侧边</div>
        <div class="content">内容</div>
    </div>
   </div>
    <!-- 底部导航 -->
  
        <ul class="footer-ul">
            <li class="footer-li">
               
                 🍔
                    <span>首页</span>
              
            </li>
            <li class="footer-li">
               
                    🍕
                    <span>分类页</span>
             
            </li>
            <li class="footer-li">
                
                  🥑
                    <span>购物车</span>
             
            </li>
            <li class="footer-li">
              
                🍰
                    <span>个人中心</span>
               
            </li>
        </ul>
</body>

<style>
    *{
        box-sizing: border-box;
        margin: 0;
        padding: 0;
    }
    .box{
        width: 100%;
        height: 100%;
        background-color: #ccc;
        display: flex;
        flex-direction: column;

    }
    html{
        width: 100%;
        height: 100%;
    }
    body{
        width: 100%;
        height: 100%;
    }
    .header{
       flex: 1;
        background-color: pink;
        line-height: 50px;
    }
    .mian{
        flex: 9;
        display: flex;
        background-color: plum;
        flex-direction: row;
    }
    .sidebar{
       flex: 2;
        background-color: orange;
    }
    .content{
        flex: 8;
        background-color: palegoldenrod;
    }
    .footer-ul{
        display: flex;
        flex-direction: row;
        height:50px;
    }
    .footer-li{
       flex: 1;
       list-style: none;
       display: flex; 
        justify-content: center;
        align-items: center;
        height: 100%;
        flex-direction: column;
    }
  
</style>
</html>